Releasably lockable structure simulating a human joint



oct. 13, 1910 J, PRAHL j 3,533,651

RELESABLY LOCKABLE STRUCTURE SIMUL'ATING A HUMAN JCINT Filed Aug. 2,1968 mfVENToR.

I. ,y Jan `Preti#0 1 -BY n United States Patent O Int. cl. Frse 11/00U.S. Cl. 287-99 6 Claims ABSTRACT F THE DISCLOSURE A structure whichsimulates a human joint and can be locked in a given position includes apair of components simulating a pair of human limbs. These componentsare pivotally connected to each other for turning movement one relativeto the other. A swingable lock member is pivotally carried by one of thecomponents and describes part of a given circle during swing movement.The pair of components are formed with lock notches which register whenthe components are in a given angular position with respect to eachother. The lock notches receive, when they register, the swingable lockmember so that with the latter in the notches the components are lockedin a predetermined position. When the notches register they are situatedalong a tangent to the circle that is described in part by the swingablelock member, and the inclination of the registering notches is such thatthey tend to press the lock member toward its locking position inresponse to any tendency of the components to move from the positionthey take when the lock notches register.

BACKGROUND OF THE INVENTION The invention relates to structures whichsimulate human joints.

Thus, it relates to jointed mechanical structures used for orthopedicpurposes or used by individuals who have su'iered paralysis of certainlimbs as to enable the limbs to be moved with the use of the structure.

In order to maintain the joint structure in a given position it isconventional to provide locking pins and detent structures, or there areswingable lock members which are capable of ybeing swung intoprojections of the joint components for releasably holding them in agiven position.

However, such conventional locking structures, situated at a givendistance from the pivot axis between the components which simulate thelimbs, are very often subjected to intense stresses and to a largeamount of wear. The reliabilityv with which the pivotallyinterconnected, limb-simulating components are locked is not suicientbecause of the possibility of a sudden jumping of the locking elementsfrom their locking positions and the manner in which the components aresupported for turning movement. With conventional structures there is anundesirable play between the components, placing the reliability of thestructure in jeopardy.

SUMMARY OF THE INVENTION It is accordingly a primary object of theinvention to provide a structure which will avoid the above mentioneddrawbacks.

In particular, it is an object of the invention to provide ajoint-simulating structure which can be very reliably held in a givenposition.

It is a further object of my present invention to provide a structure ofthe referred to type which is exceedingly simple and easy to operate,without sacricing any Mice of the reliability in the maintenance of thestructure in its locked position.

In accordance with the invention, the pivotally interconnectedcomponents are respectively formed with lock notches which register whenthe components are in a given position relative to each other. Aswingable lock member is swingably carried by one of the components toenter into the registering lock notches to hold the components locked ina given position. The registering lock notches extend along a tangent toa circle which is described, in part, by the swingable lock member.

An important advantage of the structure of the invention resides in thefact that the lock structure of the invention tends to become lockedmore tightly under load. This advantage is achieved by situating theregistering lock notches along a tangent to a circle described in partby the swingable lock member. Where the components are locked in agenerally upright position, the inclination of the registering locknotches may be on the order of 50 with respect to a horizontal plane.The pressure exerted on the lock member with such a situation of thelock notches acts at an angle of with respect to the plane of thetangent along which the lock notches extend. Thus, there is an angularrelationship which distributes the forces in such a way that the lockingelement is pressed further into the locking notches. As a result,slipping of the locking element out of its locking position while loadedis impossible.

A further important feature of the invention resides in the vfact thatthe center about which the lock member swings is situated at such alocation that a straight line drawn through this center and the lockmember itself, when the latter is in its locking position, forms withthe tangent along which the locked notches extend an angle greater than90. In this way there is achieved the advantage of additionalreliability in maintaining the structure in its locked position becausethe lock member is situated at a location analogous to the location of atoggle joint beyond its dead-center position, so that added pressureonly serves to lock the structure more tightly.

According to the invention, the lock member preferably is in the form ofa cylindrical lock pin while the notches pass through the overlappingwalls of the pivotally interconnected components, with one of thesecomponents having two integrally connected walls defining betweenthemselves a gap receiving a wall of the other component. As a result ofthis construction the lock member is loaded exclusively in shear and isotherwise relieved of all other loads. The swingable mounting of thelock member remains completely unloaded when the lock member is in itslocking position.

BRIEF DESCRIPTION OF THE DRAWING The invention is illustrated by way ofexample in the accompanying drawing which forms part of this applicationand in which:

FIG. 1 is a partly sectional side elevation of a structure of theinvention which simulates a knee joint and which is shown in its lockedposition;

FIG. 2 is a side elevation showing the structure of FIG. l, with thelock member displaced to an unlocking position; and i FIG. 3 is atransverse section of the structure of FIG. l, taken along line 3-3 ofFIG. 1 in the direction of the arrows.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawing ingreater detail, and initially to FIG. 1, there are illustrated thereinan upper limb-simulating member or bar 3 which simulates the part of aleg over the knee, while the lower part of the leg 3 which extendsdownwardly from the knee is simulated by the lower component 4. Theseparts or components are pivotally interconnected at a joint composed ofthe overlapping portions 1 and 2 of the components. The lower component4 has a pair of spaced parallel wall portions 2 integrally connectedtoeach other and delining between themselves a gap which receives the wallportion 1 of the upper component 3. A pivot member extends through theoverlapping wall portions of the components 3 and 4.

The wall portions 1 and 2 are all formed with lock notches 6 whichregister with each other when the upper component 3 extends upwardlyfrom and forms an extension of the component 4. In other words, when thelimbsimulating components have a substantially straight-line conditionwith respect to each other, the locking notches 6 register with eachother. Of course, the notches 6 of the walls 2 are permanently inregister with each other while the component 3 can turn together withthe wall 1 to a position in which a notch 6 of the latter registers withthe other notches 6. In this position it will be noted from FIG. 1 thatthe lower inclined edge of the component 3 engages the inclined surfacebetween the wall portions 2 so that counter-clockwise turning of thecomponent 3 with respect to the component 4, and clockwise turning ofthe component 4 with respect to the component 3, as viewed in FIG. 1, islimited by engagement between the upwardly directed surface between thewalls 2 and the downwardly directed edge of the wall 1. In this positionthe notches 6 register and define a common upper open inlet end and acommon closed lower end.

When the notches 6 register they extend along a tangent to a circle,this tangent being shown in dot-dash lines in FIG. 2. The tangent 7 isinclined in the illustrated upright, extended position of the components3 and 4 at an angle of 50 with respect to the horizontal, for example.

The lock member includes a pin 8 of cylindrical shape forming thelocking element and carried by a lock lever 9 which is swingable aboutthe pivot 10 carried by the component 3. The latter which has theintermediate wall 1 of the joint pivotally carries by way of the pivotpin y10 a lock member 9 which is provided with the locking element 8that is received in the registering notches. The tangent 7 is tangent toa circle described by the element 8 as it swings about the axis of thepivot 10 during turning of the lock lever 9 which can be manually turnedby the operator.

In the position of the parts shown in FIG. 1, the lock member 8 extendstransversely through the three registering lock notches 6, and thepivotally interconnected components 3 and 4 are incapable of moving withrespect to each other.

On the other hand, When the parts are in the position of FIG. 2 wherethe operator has raised the lever 9, the pin 8 is displaced from itslocking position so that the parts can now turn relative to each other.

When the parts are in the locked position shown in FIG. l, any tendencyof the component 3 to turn clockwise with respect to the component 4, orof the component 4 to turn counter-clockwise with respect to thecomponent 3, as viewed in FIG. 1, causes the developing forces to act onthe pin 8 to urge same, as seen in FIG. 1, downwardly toward the left,that is, more tightly toward the closed end of the registering notches 6so that an extremely reliable lock structure is achieved. rThis resultis brought about by providing the angle of more than 90 between thetangent 7 and a straight line drawn through the center of swinging ofthe lever 9 and the center of the lock member 8 when the latter is inits locking position. If this angle were precisely 90, then it wouldcorrespond to the dead-center position of a toggle joint. However, bymaking the angle somewhat greater than 90, an angle of 95 being shown inFIG. 1, then what corresponds to the location of a toggle joint beyondits dead-center position is achieved, with the forces locking thestructure only more tightly. Furthermore, it will be noted that becausethe pressure of the wall 1 acts on the pin 1 between the pressureprovided by the walls 2 the pin 8 is acted upon exclusively by shearingforces and the pivot 10 is completely unloaded.

I claim:

1. In a structure for simulating a human joint, a pair of componentsrespectively simulating a pair of limbs, said components being pivotallyconnected to each other for turning movement about a predetermined axisone with respect to the other, and a swingable lock member swingablycarried by one of said components for describing part of a circle duringswinging of said lock member, said pivotally connected components beingformed with locking notches which become superimposed so as to registerwhen said components are in a given angular position relative to eachother and which, when registering, receive the end of said swingablelock member, one side of each of said registering notches extendingalong a tangent to the circle described in part by the far end of saidswingable lock member, the center of swinging of said swingable lock andthe far end of the lock member itself defining the ends of a straightline forming with said tangent, when the lock member is in a lockingposition within the registering notches, an angle sufficiently greaterthan to achieve a toggle joint beyond its dead-center position.

2. The combination of claim 1 and wherein said swingable lock member hasa locking portion of cylindrical conguration received in the registeringnotches.

-3. The combination of claim 2 and wherein said components include atthe region where they are pivotally interconnected three wall portionstwo of which are integral and define between themselves a gap receivingthe third wall portion, said notches being formed in all three wallportions so that the notches in said two wall portions are permanentlyin register with each other while the notch in said third wall portioncan be displaced angularly with respect to the other notches to and fromthe registering position.

4. The combination of claim 3 and wherein said swingable lock member isswingably carried by that one of said components which has said thirdwall portion.

5. The combination of claim 1 and wherein said cornponents simulate aknee joint and are both in an extended substantially straight-lineposition when said notches register, with one of said components beingsituated over and extending upwardly from the other of said components,said notches when registering delining a common upper open end forreceiving said lock member and a common lower closed end engaged by saidlock member when the latter is in a locking position.

6. The combination of claim 5 and wherein the registering notches areinclined at an angle which urges the lock member toward said lowerclosed end of the notches when one of the components tends to turn withrespect to the other of the components in a given direction so that thecomponents are reliably locked in their extended position.

References Cited UNITED STATES PATENTS 1,226,324 5/1917 Gage 287-992,433,570 12/ 1947 Markkula 287-99 2,549,194 4/1951 Hale 287-99 DAVID I.WILLIAMOWSKY, Primary Examiner A. V. KUNDRAT, Assistant Examiner

